Projectile



1961 R. o. FRANTIK 2,996,010

PROJECTILE Filed June 50, 1944 FIG. I.

INVENTOR RUDOLPH 0; FRAN 77K ATT EY Patented Aug. 15, 1961 fire 2,996,010 PROJECTIIJE Rudolph O. Frantik, Albuquerque, N. Mex., assign'or to the United States of America as represented by the Secretary of the Navy Filed June '30, 1944, Ser. No. 543,002 2 Claims. (Cl. 102-93) This invention relates to rotary projectiles of the type which comprises a substantially full caliber sabot mounted on a subcaliber core for supporting and centering the core in a gun barrel and releasable from the core under centrifugal force when the projectile emerges from the gun muzzle. More particularly, the invention relates to a novel projectile of the character described in which the sabot is securely mounted on a projectile of conventional form, as a core, without alteration thereof and releases positively from the core under centrifugal force by a cantilever action.

One object of the invention resides in the provision of a sabot projectile having a standard projectile as a subcaliber core, and a substantially full caliber sabot securely mounted on the core by means of the annular groove normally provided in standard projectiles for receiving the turning band. 4

Another object of the invention is to provide a sabot projectile having a subcaliber core supported and centered in a sleeve-like sabot which is divided into longitu dinal segments seated at one end in an annular groove in the core and held together on the core by a frangible turning band adapted to be broken under centrifugal force by a cantilever action of the segments.

A further object is to provide a projectile of the character described in which the turning band extends around the front end portions of the sabot segments, whereby the rear end portions of the segments are operable under centrifugal force to fracture the turning band by a cantilever action and thereby release the segments from the core.

Still another object of the invention is to provide a sabot projectile of the character described which is simple in construction, positive in operation, and adapted for manufacture at low cost.

These and other objects of the invention will be apparent from the following specification and the accompanying drawing, in which FIG. 1 is a side elevational view of one form of the new projectile;

FIG. 2 is a longitudinal sectional view, partly in elevation, of the projectile shown in FIG. 1;

FIG. 3 is a vertical sectional view taken on line 33 of FIG. 2, and

FIG. 4 is a vertical sectional view taken on line 44 of FIG. 2.

The projectile comprises a subcaliber steel core having an ogive nose portion 11 and an annular groove 12 near the base of the core. The core 10 may be a conventional projectile in which the groove 12 would ordinarily receive a turning band. However, in the present construction the groove 12 receives an inwardly extending annular shoulder 13 on a sleevelike sabot 14 mounted on the rear end portion of the core. The sabot 14, which may be made of steel, is of substantially full caliber dimension and comprises a plurality of longitudinal segments fitted closely together and held in position on the core by means of a copper turning band 15. The band 15 is mounted on the periphery of the sabot segments 14 at their front end portions which are preferably provided with a plurality of annular ridges 13a into which the turning band is pressed to prevent the band from being stripped from the sabot when the projectile is accelerated in a gun barrel. It will be observed that the turning band is mounted on the sabot segments 14 directly over the annular groove 12 in the core.

The segments 14 extend rearwardly from the groove 12 and band 15 to the base of the core, the segments fitting closely against the cylindrical surface of the rear end portion of the core. At its rear portion, the sabot is thickened to provide an outwardly turned shoulder 16 and an inwardly turned shoulder 17. The shoulder 16 may be extended outwardly far enough to provide an additional bearing and centering surface for the projectile in the gun barrel, while the inwardly extending shoulder 17 fits closely around the base of the core to make a tighter fit of the sabot on the core. Together, the shoulders 16 and 17 serve to add weight to the rear end portion of the sabot for a purpose which will be explained presently.

A short plastic bourrelet 18 is preferably mounted on the core just forward of the sabot so that the rear surface of the bourrelet bears against the front surface of the sabot, thus preventing rearward movement of the bourrelet when the projectile is accelerated. The bourrelet is partially segmented by longitudinal radial cuts 19 which extend from the inner diameter of the bourrelet almost to its outer periphery, leaving an uncut portion 20 of a thickness determined by the breaking strength of the material and by the speed of rotation of the projectile.

When the projectile is fired from a gun, the turning band 15 is engraved by the rifling of the gun and imparts high speed rotation to the core through the sabot. As long as the projectile is in the gun barrel, the turning band, sabot and bourrelet are prevented from breaking apart under the centrifugal force, by the gun barrel which is in contact with these parts. As soon as the projectile leaves the gun barrel, the centrifugal force due to rotation of the projectile causes the bourrelet to break apart at the weakened portions 20 and thereby release from the core. The sabot segments 14 are normally held on the core by the rotating band 15, but the extra mass of the rear end portions of the segments due to the shoulders 16 and 17 causes the rear portions of the segments to move outwardly, under the centrifugal force, about the shoulders 13 as pivots and thereby exert a cantilever action on the turning band. This cantilever action causes the band to rupture and permits the sabot segments to release from the core. The release of the sabot and bourrelet occurs immediately after the projectile emerges from the gun barrel and leaves the core free to proceed along its trajectory without the aerodynamic drag which would result from the presence of the sabot during flight.

It will be apparent that the new projectile is of simple construction, has relatively few parts, and may be easily assembled. The core is adequately supported and centered in the gun barrel by the sabot 14, the turning band 15 and the bourrelet 18, whichare locked by the sabot shoulder 13 against longitudinal movement on the core. By reason of the cantilever action of the sabot segments on the turning band 15, the release of the sabot and turning band under centrifugal force is positive and rapid when the projectile emerges from the gun muzzle, and is effected with a relatively low energy loss and without substantially interfering with the flight of the core.

I claim.

1. In a rotary sabot projectile having a subcaliber core provided with an annual groove near the base of the core, a substantially full caliber sabot mounted on the rear end portion of the core and having an internal shoulder disposed in said groove, the sabot being divided into longitudinal segments extending rearwardly from the groove, each segment having a rear inwardly turned shoulder engaging the base end of the core, and frangible means mounted on the sabot and normally holding i139 sabot segments together on the core with the rear end portions of the segments lying to the rear of the frangible means, the rear inwardly turned shoulders of the segments being movable outwardly from the core under centrifugal force to cause the segments to exert a cantilever action on said frangible means when the projectile emerges from a gun muzzle, whereby said frangible means is ruptured and the segments are released from the core.

2. In a rotary projectile, a conventional subcaliber core having an ogive, a base and an annular groove ordinarily occupiable by a turning band, a segmented sabot having a shoulder occupying the groove in place of said band in part to leave an exposed portion, the sabot extending unfettered into overlapping relation to the base, a tuming band encircling the sabot in the region of the groove,

References Cited in the file of this patent UNITED STATES PATENTS 1,973J604 Brandt Sept. 11, 1934 FOREIGN PATENTS 131,034 Great Britain Aug. 21, 1919 801,218 France May 16, 1936 804,237 France July 27, 1936 

